Exploration on the Principle of ECMB

ECMB, which is developed by Amoco company in USA, has very prospective. On the basis of the study on adsorption characteristics of mixture gas in coal, the principle of ECMB has been explored. The order of adsorption capacities of coal for several gases is: CO 2>CH 4>N 2>H 2 when coal adsorbs gas. In 2 member mixture gases, adsorption capacities of coal for mixed gases, methane and carbon dioxide tally with Langmuir equation, but not does for nitrogen and hydrogen. The substance of the increasing drawing ratio of coal seam gas by using ECBM is decreasing adsorption amount of methane in coal by emptying the other gas or gases into coal seam. N 2 is better gas than CO 2 in the process of using ECMB.     

AB Intio Study on the Interaction between CH_4 and the Coal Surface

The atom cluster model of coal surface is proposed.Quantum chemical ab initio calculation with base set STO 4 31G indicates that the interaction between CH 4 and coal surface is anisotropy and the maximum interaction potential (or adsorption potential) is 2.65 kJ/mol,rotation potential barrier is 1.34 kJ/mol.These results have shown that the adsorption of methane on coal surface should be a physical process (that is,freezing on surface).     

Experimental analysis of coal bed methane desorption and seepage under sonic vibrating of cavitation water jets

A way to enhance coal bed methane desorption and seepage by sonic vibrating of cavitataion water jets is proposed because the gas coal seams have the intrinsic properties of micro-porosity, low permeability and high adsorption. The mechanisms of how the sonic vibrating effects promote methane desorption and seepage are analyzed, and the contrast experiments of methane desorption and seepage under sonic vibrating effects are also provided. The results show: when the cavitation number is 0.020 0, under sonic vibrating effects, the volume of coal bed methane desorption increases by 36.9%, and the time for coal bed methane desorption reduces by 19.6%. The speed of coal seams methane seepage is significantly increased by 35.3% and arrives at 0.383 3 ml/s.     

Study on Adsorption Characteristics of Coal to Gas in Geophysical Field

It is very important to mine safe exploitation, gas drawing and predict of coal and gas outburst that adsorption characteristics of coal to gas in geophysical field are studied. Adsorption and desorption characteristics of coal to gas in geophysical field have been reviewed in detail, then it is obtained that adsorption characteristics of coal to gas in electromagnetic field should be further studied . Adsorption and desorption characteristics of coal to methane in alternating electric field (AEF) have been studied mainly. Adsorption characteristics of three coal samples in AEF have been studied by means of Volume Method. The result shows that chemical properties and matter constituent of coal surface are no changed , adsorption and desorption of the coal samples in AEF well accord with Langmuir equation and two constants empirical formula, and because coal potential energy is increased and coal temperature is raised caused by Joule heat effect , adsorption ability of coal is decreased, and the desorption process is slowed down in AEF.     

Economic Benefit Analysis on the Exploitation and Utilization Coal bed Methane

The gas accident in Coal Mine is an important safe hidden trouble.The notion on the prevention and cure of gas accident should be changed.Coal gas is a kind of deleterious gas,but it is a clean energy resource.The actualities of coal bed methane resources and its use in our country are reviewed.The foreground for the use of coal bed methane is analyszed.The economic benefit of coal bed methane utilization is evaluated by the Net Present Value(NPV) and the Internal Rate of Return(IRR)method.The results are shown that the utilization of the coal bed methane can decrease the gas accident,save energy source,reduce the environmental pollution,and have remarkable economic benefit.     

Mechanism and application of protection againstoutburst for abrasive water jet slotting technology

Aiming at the status quote of long time for methane extraction and slow speed for laneway excavating in coal seams of Liziya south 2JHJ well, abrasive water jet slotting technology is adopted to improve the methane desorption and increase excavating speed in semi-coal laneway. Through analyzing damage model and protection against outburst mechanism, the process of Coal-Rock Mass being cut and fractured is studied. Through lab test on abrasive water jet cutting coal-bed gangue, a new abrasive water jet cutting device is successfully designed and made and all parameters are determined. It is showed that abrasive water jet can cut through a coal-bed gangue with thickness 60~80 mm and uniaxial compressive strength 62 MPa. After cutting coal seams by abrasive water jet, the surface area for methane is enlarged and then coal seams pressure fell rapidly. Therefore the permeability and desorption of coal seams are greatly increased. The results are as follows: the average productivity of single-hole was enhanced by 2.83 times.     

Experimental analysis of matrix shrinkage’s influence on mechanical permeability of gas filled coal

Based on the coal seam of Zhao zhuang coal mine and Si he coal mine belong to Jin cheng anthracite Mining Group in Shanxi province, by using the self developed three axial servo controlled seepage equipment for hot fluid solid coupling of coal containing methane, parallel experiments for permeability of helium and methane under different gas pressures are carried out to quantitatively study the influence of Klinkenberg effects on the permeability of coal. Meanwhile, the problem of permeability decreasing caused by fluid pressure decreasing and gas desorption is eliminated by controlling the effective stress. The results show thatthe Klinkenberg effect is obvious under low gas pressure. With the increase of gas pressure, the permeability of coal decreases at first and then increases. The inflection points of gas pressure for Klinkenberg effect are about 0.9 MPa both for coal samples in Zhao zhuang coal mine and Si he coal mine. When the effective stress is constant, with the increase of gas pressure, the permeability increment caused by Klinkenberg effect decreases, while permeability increment caused by coal matrix shrinkage increases. Coal matrix shrinkage has a close relationship with the mechanical properties of coal rock mass. For the coal sample with a poor mechanical property, coal matrix shrinkage is more obvious.     

Numerical simulation on low calorific value coal-bed gascombustor and structural design optimization

This paper conducts the full size three-dimensional combustion numerical simulation study on the low-calorific value coal bed gas combustor. It explors the effects of different ratios of swirling wind and straight wind on flow field,temperature field and concentration field when this combustor combusts coal bed gas which methane volume concentration is 30 percent. The optimal ratio of swirling wind and straight wind is gained. Based on this,the number and obliquity of cyclone vane in gas pipeline are further optimized. The results show that when ratio of straight wind is 80 percent and ratio of swirling wind is 20 percent,the good jet flow rigidity is not only possessed,but also the strong spin momentum is brought. Reverse axial velocity grads and reverse velocity in central backflow region are also big,the burning temperature and combustion efficiency are high,and high-temperature region is diffusely distributed. When the number and obliquity of cyclone vane are respective 6 and 60,the mass fraction of methane descends quickly,the mass fraction of methane is low in outlet of combustion region,and the combustion efficiency is high.     

A Numerical Simulation of Coalbed Methane Desorption and Diffusion Enhanced by Ultrasound Heating

We discuss the development of coal bed micro structure and the mechanism of enhancing the desorption/diffusion of coalbed methane by ultrasound. We present a mathematical model to describe the desorption/diffusion process of coalbed methane due to the ultrasound heating effect. Two cases of gas release with or without ultrasound fields in coal samples were simulated. We found that the temperature and the micropore diffusion coefficient of the system were improved by ultrasound transferred heat energy, while the dynamic fraction of free gas in pores was enhanced and the dynamic fraction of adsorbed gas was weakened.     

生物炭对土壤N2O和CH4排放影响的研究进展

为了探讨生物炭对土壤N2O和CH4排放影响的途径和机理,在综合评述前人研究的基础上,就生物炭对土壤N2O和CH4排放的影响因素、途径和影响机理进行了分析,提出了不同土壤的生物炭施用原则,并指出了今后生物炭研究应注意的问题:(1)明确土壤中2种温室气体排放特点,园地制宜地选择合适的生物炭类型;(2)注意生物炭的添加时机和用量;(3)目前学者所用的生物炭类型以及土壤种类不同,关于生物炭影响土壤N2O和CH4排放的研究结论不同.在这方面的研究工作还应在完善生物炭施用标准的基础上,继续进行生物炭还田的本地化试验验证,才能为生物炭对土壤N2O和CH4排放的影响得出更明确的结论.     

Effects of Livestock Wastewater NH4 +-N Incubation on Landfill CH4 Oxidation by Mineralized Refuse Particle

Ammonia oxidizing bacteria was accumualted for landfill CH4 oxidation in the mineralized refuse throguh livestock wastewater NH4 +-N incubation, which would minimize the total Greenhouse gas emission equivalent from MSW landfill. Mineralized refuse was firstly incubated by livestock wastewater NH4 +-N during the 120d operation. Mineralized refuse possessed the strong nitrification capacity with the removal rate of NH4 +-N content over 60% during the 120 d operation. After 200 mg N kg -1 was inputted, NO3 --N content produced from the 120 d incubated mineralized refuse was 2.0-time and 3.8-time more than those of the original mineralized refuse and clay soil, respectively. CH4 decrease and the net produce of CO2 can be well fitted the one- and zero-order kinetics model during the 120 h incubation (R 2>0.68), respectively. Similar as nitrogen turnover, CH4 oxidation capacity from the 120 d incubated mineralized refuse was 10.6% and 59.3% more than those of the original mineralized refuse and clay soil, respectively. Therefore, the mineralized refuse can be upgraded for the CH4 oxidation throng NH4 +-N content incubation from the livestock wastewater and the influence on CH4 oxidation by other components (including CODCr, SS and phosphate) from wastewater should be further investigated.     

Investigation on the reaction characteristics of methane catalytic partial oxidation in a micro-channel

The reaction characteristics of fuel-lean CH4 catalytic partial oxidation over Rh are investigated numerically in a micro-channel, by using detailed elementary mechanism, focusing on the effects of inlet temperature, equivalence ratio of CH4/O2 and added H2O on catalytic partial oxidation of CH4. The results show that over Rh surface reaction of CH4 is kinetically controlled, while that of O2 is controlled by mass transport. Duo to the high reactivity of O2, CH4 is firstly oxidized and both complete and partial oxidation products are generated. After O2 is consumed, steam reforming begins, however, CO2 reforming does not appear. Increase of the equivalence ratio of C/O leads to increase of carbon deposition at reforming zoon, as thus both conversion of CH4 and production of syngas decrease, even the reforming process is stopped. The added H2O could dramatically inhibit carbon deposition, and promote the formation of H2 and CO2.     

THE EFFECT OF THE STRESS OF LONGWALL AND STRUCTURE OF COAL ON THE BUMP OF COAL AND METHANE

The problems that the bump of coal and methame in the mine is contraled by the stress of longwall and that the coal and methane bump in the mine is affected by the physical properties of the coal are analysed and discussed through some specific bump cases. It is shown that the compressive stress, the content of the methane of the coal, and the bump of coal and methane are directly affected by the content of the ash and the volatile of the coal.     

稻田甲烷排放研究进展

甲烷是一种重要的温室气体,而稻田是甲烷的重要排放源之一。因此,对稻田甲烷排放进行研究具有重要的意义。阐述了稻田甲烷产生、氧化及传输的机理,归纳了稻田甲烷排放的日变化、季节变化、年际变化等规律,重点分析了稻田甲烷排放的影响因子,包括温度、水分、土壤有机质、土壤氧化还原电位、土壤pH、施肥等。     

四川农村户用沼气温室气体减排量估算与能源环境效益分析

为研究中国西部农村贫困地区推广使用户用沼气产生的温室气体（GHG）减排量和能源与环境效益,以四川省凉山州农村中低收入家庭户用沼气项目为例,利用联合国清洁发展机制（CDM）方法学AMS-III.R和AMS-I.C估算其GHG减排量,并对其能源与环境效益进行分析。项目涉及14个县的35656农户,研究结果显示,户均GHG减排量在1.8~2.5 t CO₂ e范围内,整个项目35656口户用沼气池共带来GHG年减排量约为72898.2 t CO₂e。同时,每年直接节省约2.16万t原煤使用与648万元原煤购买费用,直接年产出约1978万m3沼气清洁能源,直接减少SO2排放约288440 kg、减少NOx排放约31320 kg、减少烟尘排放约15120 kg。研究表明,农村户用沼气的使用,一方面,既能减少目前生猪粪便管理方式造成的CH4排放,又能充分利用农村沼气清洁能源,减少因煤炭使用而产生的CO₂排放;另一方面,又能带来可观的能源与环境效益。此外,依据CDM方法学估算农村户用沼气项目GHG减排量,能为中国农业领域温室气体排放的监测、报告、验证（MRV）提供量化依据和借鉴。     

Experimental study on permeability rules of coal considering sorption and long-term stress

The paper studies the permeability rules of coal during methane sorption and long-term triaxial load by self-manufactured triaxial permeation apparatus. The experimental coal samples are excavated from Fuxin Stratum Coal seam of HengDa Coal Industry Co., Ltd in Fuxin city. The experiment results show that: the value of coal permeability considering methane adsorption is lower than that without methane adsorption, reducing by 48.94%~82.18%; slippage effect exists in coal after sorpting methane. Coal permeability has significant reduce by 82.05%~92.65% under 18 MPa total stress after 78 day, coal permeability variations with time can be described by negative exponential function. The value of permeability of coal sample is higher than that without stress release condition, but is lower than that under initial condition, which is loaded again after stress release. The value of coal permeability is higher than reservoir permeability under initial stratum condition by current experiment methods.     

Coal and gas outburst disaster early warning andemergency response decision support technology

In order to realize early warning of coal and gas outbursts, and take timely emergency response, the technology of coal and gas outburst early warning and emergency response decision support is brought forward. The characteristics of abnormal gas outburst are specially analyzed, thus methods are given to monitor and identify the coal and gas outburst disaster. Combined with existing safety monitoring system in the mine, researches of such techniques are carried out as outburst gas content predicting, spread range forecasting and regions of power cutoff. Through those techniques, the Daping coal mine gas explosion disaster is retrieved. In the process of simulation, gas spreading early warning and related emergency response proposals can be issued before the gas arrive.     

稻田耕作制度对CH4气体排放影响的研究进展

甲烷是重要的温室气体,其辐射增温效应是CO2的20~30倍。稻田是CH4的重要排放源之一。稻田CH4的排放是稻田CH4产生、氧化和传输综合作用的结果。影响稻田CH4释放的因素众多。本研究从水稻的农耕制度角度总结近年来关于稻田CH4排放的影响因素的研究,系统地归纳了水稻生物学特性、品种栽种方式、水肥管理等方面对CH4气体排放影响,同时从耕作角度提出了稻田CH4减排的技术措施。     

Application the hydraulic fracturing technology in the highn pressure and low permeability mine

To solve the gas drainage problem of the high gas and low permeability mine, based on the features of the high pressure water, the hydraulic fracturing technology is proposed to improve the gas drainage rate. According to the first strength theory, through analyzing the stress around the borehole, the broken mechanism of the coal under high pressure is studied and the function of critical value is obtained. In addition, based on the coal features of the tenth mine of the Pingdingshan, the fracturing pressure is calculated and the hydraulic fracturing parameter is optimized. The equipment of the hydraulic fracturing technology is developed and applied successfully in the mine. And it is found that the gas drainage flux and concentration are improved with more than 5 times.     

THE EFFECT OF STRESS ON PERMEABILITY OE COAL AND POROUS ROCK AND FRACTURED ROCK

In this paper, the permeability of coal, porous rock (sandstone), fractured rock(limestone) varifies with different confining pressure is discussed. Exponential functions between permeability and confining pressure are concluded. As a primary exploratiotion of permeability, it is significant to study coal and rock seepage characteristics and methane emission prediction. It is also useful in mine methane drainage system design.